There were cheers and applause in Courtroom Number 6 of the Criminal Courts of Justice when the verdict was announced, with one man shouting “you sc*mbag, junkie b*****d” at the defendant.

McDonald did not react when the verdict was delivered after two hours and six minutes of deliberations by the jury.

The defendant, from the East Wall area of Dublin’s north inner city, had pleaded not guilty before the Central Criminal Court to the murder of Mr Walker in the car park of Blanchardstown Racing Pigeon Club in Clonsilla on June 12, 2015.

Mr Walker was at the pigeon club because he had offered to deliver his friend Jason O’Connor’s pigeons to the club as they were involved in a race the next day.

Mr O’Connor was banned from driving at the time, and Mr Walker drove Mr O’Connor’s partner’s car over to the club.

It was the prosecution case that Mr McDonald disguised himself as a woman and shot Mr Walker 18 times with a sub machine gun. He died at the scene as a result of multiple gunshot wounds to his head and body.

Eye-witnesses had described hearing shouts of "hitman", before shots were fired and they "hit the floor".

The court had heard during the trial that McDonald was wearing make-up, a long black wig, sunglasses, black gloves, black leggings and a black cardigan when he carried out the shooting.

He had stopped two teenagers on the street and asked them for directions to the pigeon club, and asked one of them if he could use his mobile phone.

In her evidence, State Pathologist Professor Marie Cassidy said the cause of Mr Walker’s death was multiple gunshot wounds to his head and upper body, with contributing factors the gunshot wounds to his limbs.

Prof Cassidy said Mr Walker was struck by 18 bullets, mostly on the left side of his body. Two of the bullets struck the left side of the dead man’s head.

The head wounds would have resulted in the “rapid death” of Mr Walker, the jury heard.

DNA matching McDonald was identified on a glove and wig found alongside the sub-machine gun used in the attack.

Dr Edward Connolly of Forensic Science Ireland tested a number of items, including a glove, wig, brown handbag, ear plug and sub-machine gun found in a laneway at Sheepmore Grove in Blanchardstown after receiving a tip-off from a local resident.